Outdoor lighting has evolved over the years from the earliest use of incandescent lamps, through the use of fluorescent, high intensity discharge (HID), and mercury-vapor lamps, and more recently to light emitting diode (LED) lamps. LED lamps offer several advantages, including improved quality, performance, lifespan and cost, and their use and popularity have been growing. LED lighting also provides, and has the potential for further providing, reduced power consumption per unit lumen.
One drawback of LED lighting systems is the cost and inconvenience of removing conventional, non-LED-based light fixtures and installing new light fixtures that are design and optimized for LED-based lamps. To defray this expense, attempts have been made to retrofit, or force-fit, LED lamp technology into non-LED lamp fixtures. Examples include the incorporation of LED lamps inside and on the outside surface of “bulb” style lamps, with threaded electrical connections so that the LED bulb lamp can be screwed into a conventional socket.
An alternative means for retrofitting LED lamps into a conventional light fixture is to replace both the conventional bulb and the electrical socket with an LED lamp assembly which incorporates or is augmented with a suitable power and control systems for LED service. Nevertheless, such retrofitting efforts often fail to address one or more of the functional differences characteristic of LED lamps. In particular, LED lamps are sensitive to heat generated by the LED itself, and may lose efficiency unless the heat and local temperature increases are minimized. LED lamps are also well known to emit light in a lambertian distribution, whereas most conventional incandescent and fluorescent lamps emit a spherical light pattern. Positioning and controlling the light emitted from an LED requires a different technique than the light from a conventional lamp. Furthermore, typical power converters that convert off-line (110-377V AC) to 24V, constant current to drive the LEDs, are bulky and do not conveniently install into such socket-type light fixtures.